A VPS Server I had just wasn't working right, code that I migrated there just wasn't working. For example, it kept telling me the connection to the database was unsuccessful, halfway through iterating through results it already had.
Then I realized it wasn't my code. I checked my /proc/user_beancounters and found this:
cat /proc/user_beancounters Version: 2.5 uid resource held maxheld barrier limit failcnt 2000: kmemsize 2499074 3453079 268435456 268435456 2985 lockedpages 0 8 999999 999999 0 privvmpages 43361 87480 1024000 1024000 0 shmpages 671 1647 65536 65536 0 dummy 0 0 0 0 0 numproc 32 48 999999 999999 0 physpages 10119 24142 0 2147483647 0 vmguarpages 0 0 1024000 1024000 0 oomguarpages 10119 24142 6144 2147483647 0 numtcpsock 6 24 7999992 7999992 0 numflock 8 12 999999 999999 0 numpty 1 1 500000 500000 0 numsiginfo 0 6 999999 999999 0 tcpsndbuf 69316 380120 235713536 235713536 0 tcprcvbuf 98304 1527656 235713536 235713536 0 othersockbuf 8944 175584 235713536 235713536 0 dgramrcvbuf 0 8380 235713536 235713536 0 numothersock 12 32 7999992 7999992 0 dcachesize 220365 274667 2147483646 2147483646 0 numfile 1116 2025 23999976 23999976 0 dummy 0 0 0 0 0 dummy 0 0 0 0 0 dummy 0 0 0 0 0 numiptent 5 5 128 128 0
Notice the "failcnt" for "kmemsize" is 2985. The value was too low, in this quote it had already been corrected and after that my PHP scripts were working fine.
When things don't make sense and aren't working properly, check your "beancounters" to make sure nothing is failing.
Also remember not to instantly blame your VPS Provider, lots of times people have these problems when running intensive scripts, applications, CPanel/Plesk and it's because your plan does not have enough RAM etc...
This should be something every admin/owner of a VPS checks routinely for inexplicable problems/timeouts with your applications in a VPS Server.
OpenVZ technology is the best for performance, but the settings must be just right to avoid problems, and you must make sure you have a plan that meets your needs. There's no such thing as swapping, if you exceed your limits, connections drop, application/database calls fail without explanation.
So just remember to pick a VPS/Virtual Private Server plan that meets you needs and monitor the beancounters for any signs of failures.
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